Research progress of functional atomic force microscopy at the interface of polymer nanocomposite dielectrics

The interface is one of the most important factors affecting the macroscopic properties of polymer nanocomposite dielectrics. However, the study of the interface still faces many challenges, such as the evolution mechanism of the interface microstructure, interface compatibility, interface polarization, and the internal mechanism of crystallization. Due to the lack of direct observation and characterization of the interface, the theoretical research is seriously hindered. The influence of the nanoparticles embedded in the nanodielectric and the interfacial region on charge transport and accumulation is still unclear. Since the nanoscale interface is beyond the spatial resolution of traditional analytical techniques, the understanding of the interfacial charge behavior of polymer nanocomposites is largely dependent on speculation and indirect experimental results. Atomic force microscopy (AFM), as a nanometer high-resolution measuring instrument, has become an important means to study the interfacial microregions of polymer nanocomposite dielectrics. In this paper, the latest research progress of various interface models and functional AFM in interface structure, charge transport, and interface polarization are reviewed. The existing problems and possible development directions in the future are also discussed.

Graphical Abstract

Nanodielectrics show excellent dielectric properties, and many scholars try to explain this phenomenon from different angles, among which, the interface effect between nanoparticles and polymer matrix has aroused great interest of researchers. However, due to the complexity of the interface region, it is impossible to intuitively obtain the microstructure and interaction mechanism between the polymer chain and the nanoparticles in the interface region, so researchers have proposed different interface models to speculate and explain the macroscopic properties of the nanocomposites. Such as diffusion electric double layer model, multi-core model, interphase volume model, double layer model, water shell model, multi-zone structure model, penetration theory model, three-dimensional electrostatic model, deep trap model, etc.